The Ulla is the third longest river in Galicia after the Miño and the Sil. Even its estuary in the Ría de Arosa becomes a rich natural corridor that receives contributions from a dense network of tributaries such as the river Sar, sung about by Rosalia de Castro, and the Deza. Precisely in one of the tributaries of the latter lies the River Toxa waterfall. A beautiful footpath connects the waterfall, in the hamlet of Pazos, with the Monastery of Carboeiro. The hardness of the stone at this site results in one of the most spectacular falls in Galicia with a steady mist in the air. Amongst all that green, the moss does not mislead. If water is life, then the Toxa waterfall embodies the joy of living.
As for the flora in the Deza, there is varied riverside woodland which is well maintained. Dominated by Alder (Alnusglutinosa), Willow (Salix atrocinerea) and Narrow Leaved Ash (fraxinusangustifolia) that incorporates, among other species, Oak (quercusrobur), Pyrenean Oak (quercuspyrenaica), holly (Ilex aquifolium), Galician-oak, Portuguese Alder and Buckthorn (rhamnusfranguía).
In the case of wildlife, both rivers have an important fish population in addition to the estuary related species such as Atlantic salmon (Salmosalar) and sea lamprey (Petromyzonmarinus), also worth highlighting are the trout, Carp (cyprinids) and the Iberian Nase (Pseudochondrostomapolylepis) as well as the freshwater mussel.
In the stretch of the Deza River which defines Silleda, it is interesting to visit the medieval Bridge at Taboada, along the Via da Prata, the surroundings of Carboeiro Monastery, the Toxa waterfall and the mouth of the river Deza where it joins the Ulla, in the parish of Cira.
There is clearly marked for the delight of visitors a path connecting the Toxa Waterfall with Carboeiro Monastery.